1. Field of the Invention
The invention relates to lift assemblies for axles of the trailer of a semi-trailer, and in particular to lift assemblies located generally adjacent to and beneath beams of suspension assemblies of the trailer. More particularly, the invention is directed to an underbeam axle lift assembly which operates efficiently and provides clearance for location of a dual brake chamber generally adjacent to and beneath the beam, and which facilitates installation and removal of the dual brake chamber.
2. Background Art
It is a common practice to lift one or more of the trailer axles of a semi-trailer and to maintain the lifted axles in a raised position, which in turn causes the wheels and tires attached to the raised axles to be lifted off of the ground. Removing certain ones of the semi-trailer wheels and tires from ground contact typically is done when the trailer is free of payload and less than all of the wheels/tires of the trailer can adequately support the unloaded trailer. This results in improved turning radius and maneuverability of the trailer. Another common reason for lifting the axle simply is to reduce wear on the lifted axle, wheels and tires when the vehicle is traveling in an unloaded condition. It should also be noted that axle lifts have been utilized on vehicles other than semi-trailers.
Axle lift assemblies have been utilized for many years in the semi-trailer industry and can be found in various designs. However, the designs typically are of the overaxle-type, that is, the lift assembly is mounted above the suspension assembly beam and inboard from the suspension beam and above the axle. Unfortunately, while such designs achieve their intended function of lifting an axle, the overaxle designs are costly to manufacture because they typically require additional structures, such as brackets and the like, to be mounted on the frame of the trailer or vehicle in order to support the lift assembly. This increased complexity of such top-mounted lift assemblies also results in increased installation and maintenance costs. Moreover, such additional support structure adds unwanted weight to the vehicle. Also, the many different trailer and vehicle designs, as well as the various axle/suspension systems that support them, involve different degrees of clearance, so that typically one type of lift assembly is suitable only for certain applications.
Due to the above-noted limitations of top-mounted lift assemblies, axle lift assemblies mounted beneath suspension assembly beams have become popular, particularly in Europe. This popularity can be attributed to the fact that the lift assembly mounts directly to the suspension beam and its support structure, and is free of additional support brackets and the like. However, it should be noted that in Europe trailer axles must be grouped in a tri-axle arrangement or three axles together. According to European regulations, only two of the three grouped axles are required to have a parking brake or emergency brake chamber, in addition to a service brake chamber. Specifically, a service brake chamber applies braking force to a vehicle when pressurized air is supplied to the chamber during operation of the vehicle. A parking brake chamber applies braking force to the vehicle when the vehicle is shut down or parked, and a spring contained in the chamber applies that braking force when pressurized air is removed from the chamber due to the shut down or parking of the vehicle. Since such parking and service brake chambers also are mounted beneath the suspension beams, the lift devices, when used, typically are installed beneath an axle lacking a dual parking/service brake chamber, and having only a service chamber, due to space considerations.
Thus, since underbeam lift devices evolved in Europe for applications in which brake chambers were mounted on the axle inboard from the suspension beams, or for applications in which only a service brake chamber was mounted in the area beneath the beam, clearance is lacking for mounting of the same type of underbeam axle lift assembly in United States applications having a dual brake chamber mounted beneath the beam. Unfortunately, in the United States, most trailer axles are grouped in a tandem configuration or two axles together, and are required by United States regulations to each have service and parking brake chambers. The same regulations generally also apply to vehicles other than semi-trailers, such as dump trucks and cement mixer trucks, which are commonly and collectively referred to as straight trucks. Thus, any underbeam axle lift assembly must accommodate the reduced clearance caused by the United States dual brake chamber requirement. The European type underbeam axle lift assembly simply fails to fit within such space constraints. Thus, the need has existed for a lift assembly that can be mounted beneath a suspension assembly beam despite the presence of a dual brake chamber beneath that beam, and still efficiently raise the axle and be easily removed and replaced, enabling removal and replacement of the dual brake chamber.
The present invention solves the above-described problems by providing an efficient air spring-driven axle lift assembly that is removably mounted on the suspension assembly beam and its hanger bracket without encroaching into the space of the dual brake chamber, and which can be easily removed and reinstalled for facilitating installation or removal of the dual brake chamber.
Objectives of the present invention include providing an axle lift assembly which can be mounted beneath the beam of a suspension assembly without interfering with an underbeam mounted dual parking/service brake chamber.
A further objective of the present invention is to provide such an underbeam axle lift assembly which operates more efficiently and is subject to less wear than prior art underbeam axle lift assemblies.
Another objective of the present invention is to provide such an improved underbeam axle lift assembly which can be quickly and easily removed and reinstalled to enable removal and installation of a dual brake chamber.
These objectives and advantages are obtained by an assembly for lifting a beam and an axle of an axle/suspension assembly, the assembly including means mounted generally adjacent to the beam and generally below an upper surface of the beam, for generating a force for lifting the axle and the beam, the lift assembly enabling disposition of a dual service/parking brake chamber generally adjacent to the beam and generally below the upper surface of the beam.